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[IEEE 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM) - Cuenca, Ecuador (2018.10.15-2018.10.19)] 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM) - Reliability in GaN-based devices for power applications
摘要： This paper analyzes two important reliability issues in AlGaN/GaN devices: positive bias temperature instability (PBTI) and time-dependent dielectric breakdown (TDDB). The summarized results of our previous PBTI studies in MOS-HEMTs show that the threshold voltage degradation in devices with SiO2 as gate dielectric is characterized by a universal decreasing behavior of the trapping rate parameter and is ascribed to charge trapping in the SiO2 and at the SiO2/GaN interface. On the contrary, the degradation observed in Al2O3- and AlN/Al2O3-gate stacks is mainly attributed to charge capture in the pre-existing dielectric traps with a negligible interface state generation. Additionally, the insertion of a thin AlN layer impacts on the device reliability because larger trap density, faster charge trapping, wider trap energy distribution and slower charge release are observed compared with devices without this layer. The dielectric importance of GaN-based devices has been also investigated in Schottky Barrier Diodes (SBDs) with a gated edge termination (GET). Our recent TDDB results indicate a narrower Weibull distribution, and a longer time to failure in devices with a double GET layer structure and with a thick passivation layer (2 GET-THICK) than in single GET devices with a thin passivation (1 GET-THIN). Therefore, the former structure is more suitable for high-power and high-temperature applications.
关键词： TDDB,AlGaN/GaN SBD,trapping,de-trapping,reliability,PBTI,breakdown voltage,GET,MOS-HEMT
更新于2025-09-23 15:23:52
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Two-step Degradation of a-InGaZnO Thin Film Transistors under DC Bias Stress
摘要： A unified explanation is proposed to consistently explain the two-step degradation of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) under DC positive bias temperature instability (PBTI) stress without or with different drain stress voltages (Vds). For PBTI stress without stress Vds, this initial negative Vth shift is believed to be induced by donor-like defect states corresponding to H2O molecule and intrinsic defects, while for PBTI stress with stress Vds, the negative shift is believed to be induced by donor-like defect states corresponding to oxygen vacancies. The gate-bias-induced electron trapping mechanism is responsible for positive Vth shift. These transitions from negative to positive Vth shift are resulted from the competition between the donor-like states creation and electron trapping.
关键词： PBTI,donor-like states creation,two–step degradation,electron trapping,IGZO TFTs,H2O molecule
更新于2025-09-23 15:21:01
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CMOS 256-Pixel/480-Pixel Photovoltaic-Powered Subretinal Prosthetic Chips With Wide Image Dynamic Range and Bi/Four-Directional Sharing Electrodes and Their Ex Vivo Experimental Validations With Mice
摘要： After nearly half a century of research into the bias temperature instability, two classes of models have emerged as the strongest contenders. One class of models, the reaction-diffusion models, is built around the idea that hydrogen is released from the interface and that it is the diffusion of some form of hydrogen that controls both degradation and recovery. Although various variants of the reaction-diffusion idea have been published over the years, the most commonly used recent models are based on nondispersive reaction rates and nondispersive diffusion. The other class of models is based on the idea that degradation is controlled by first-order reactions with widely distributed (dispersive) reaction rates. We demonstrate that these two classes give fundamentally different predictions for the stochastic degradation and recovery of nanoscale devices, therefore providing the ultimate modeling benchmark. Using detailed experimental time-dependent defect spectroscopy data obtained on such nanoscale devices, we investigate the compatibility of these models with experiment. Our results show that the diffusion of hydrogen (or any other species) is unlikely to be the limiting aspect that determines degradation. On the other hand, the data are fully consistent with reaction-limited models. We finally argue that only the correct understanding of the physical mechanisms leading to the significant device-to-device variation observed in the degradation in nanoscale devices will enable accurate reliability projections and device optimization.
关键词： NBTI,dispersive reaction rates,first-order processes,PBTI,Bias temperature instability,reaction-diffusion,oxide defects,charge trapping
更新于2025-09-19 17:13:59